Described below is a method and an assembly for determining cell vitalities. The method includes binding living cells to magnetic particles, application onto a sensor array, uniform distribution over the sensor array, magnetic immobilization of the magnetic particles with the bound cells over the sensor array, and application of substances for maintaining and/or improving the cell vitality onto the sensor array, and/or application of substances for worsening the cell vitality onto the sensor array. The assembly includes a sensor array composed of sensors which are configured to be in direct fluidic contact with a fluid, and a device for generating a magnetic field over the sensor array.
In microbiology, a large number of methods are known for the study of pathogenic microorganisms on the basis of cell culture and antibiotic resistance tests. The “phenotypic” approach, in which the action such as for example the growth or the inhibition of cell growth is studied, is advantageous. Via the action on cell cultures, a direct reference to the action on man or animals can be obtained. In this, cell cultures are placed in a nutrient solution for days on end, e.g. in Petri dishes, and observed. The growth or the damage to the cell cultures is measured and assessed over long periods. The long periods which are necessary for the observation make the method very costly and time-consuming.
For measuring the growth or the damage to the cell cultures, sensor systems can be used. Living cells are for example grown on sensors in order then to monitor the vitality of the cells for example by measurement of impedance, oxygen or pH. As sensors, interdigital electrode arrays, oxygen sensors or pH sensors can be used. Measures of the vitality of the cells are inter alia their adhesion to surfaces, their respiration or their metabolism. However, growing the cells on the sensors is time-consuming and leads to limited storability of the sensor systems. Cells that have grown on the sensors can migrate on the surface and/or die off.
For measurement of the vitality of cells via an oxygen or pH value, a defined liquid film between a cell wall and a sensor surface is necessary. With direct growth of the cell wall on the sensor surface, the defined liquid film can be lost. This can lead to impairment of the measurement, right down to the case wherein a measurement becomes impossible.
For a reliable measurement, it is also necessary that the sensor surface be free from dead cells. For this reason, before each treatment or measurement interval, dead cells must be removed from the sensor surface. This is as a rule effected by reagents, which is associated with expenditure and can lead to damage to the sensor surfaces. This prevents comparable and reproducible measurements.
Hence, described below are a method and an assembly for determining cell vitalities, which allow rapid and simple as well as reliable measurement of parameters which are typical of cell vitality. At the same time, error factors, such as for example the migration of cells on the surface or measurement errors due to direct surface growth with no liquid film between cell and sensor surface, should be excluded.